DE2547461A1 - METHOD FOR CLEANING A RAW C LOW 5 -C LOW 30 -PARAFFIN- ON-OXIMS OR. -OXIME MIXTURE - Google Patents

Description

Method of Purification of a Crude C Paraffin-on oxime or oxime mixture

The invention relates to a method for the purification of a crude oxime or oxime mixture, the substantial amounts of Contains carbonyl and chlorine compounds as impurities. More specifically, the invention relates to a method for the purification of crude oximes, the photolytically catalyzed liitrosation of mixtures of paraffins with 5 30, preferably 10-15 carbon atoms, preferably using from hitrosyl chloride and hydrogen chloride.

Oximes are valuable lubricant additives and additives for Antifreeze. They are also versatile organic intermediates; you can after Beckmann can be rearranged, alkoxylated and hydrogenated. Some oximes can be converted into synthetic fibers (cyclohexanone oxime e.g. can. to. Caprolactam are hydrolyzed, which is an intermediate in the manufacture of polyamide 6).

609821 / Q973

Paraffin-on-oximes were made by base-catalyzed reaction of ketones with hydroxyl amines and are more recently produced by photolytic ITitrosation of η-par affins. In both processes, a crude product is obtained which has considerable amounts of impurities boiling near the boiling point of the oxime, or the boiling points of the impurities overlap with that of the oxime. Most of these impurities are common with these Processes' occur are aldehydes and ketones (commonly referred to herein as carbonyl compounds), while at photolytic process crystalline (like) ITitrosochloride and crystalline ITitrosochloride condensation products as well Can cause disconnection difficulties. In any case, the usual high vacuum distillation fails with crude, oxime obtained by photolytic ITitrogenation in order to produce highly pure, i.e. to achieve at least 95% by weight oxime that is free of ketones. Examples 1 below and confirm this.

The invention is based on the object of providing a process for the purification of crude oximes which contain considerable amounts of carbonyl and organic chlorine compounds as impurities. In particular, a simple process for the purification of crude oxime, which has been obtained by photolytic nitrosation of η-paraffins, - for example according to the process described in German patent application P 21 15 04-9 of the applicant - the substantial amounts of carbonyl and / or containing organic chlorine compounds as impurities. The method should be applicable to raw products with an oxime content of 95 ° / ° and below and lead to products with an oxime content of at least 98% by weight. It should work economically and be easy to implement.

The object is achieved by a method for purifying a crude Cc-C ^ Q-paraffin-on oxime or oxime mixture an oxime content of max. 95 wt .-? a, that with carbonyl compounds and chlorine compounds is contaminated, which is characterized in that a mixture of the to

6 0 9 8 2 1/0 9 7 %

cleaning paraffin-on-oxime and, based on one part by weight this paraffin-on-oxitas, about 0.01-0.2 parts by weight Water and about 0.02-0.5 part by weight of an alkanol with 1-5 carbon atoms, 0.1-1 part by weight urea "or thiourea be admitted

this Keaktionsgeraisch to 25 - 200 ⁰ C is heated until the organic chlorine compounds is decomposed and an insoluble urea or thiourea-carbonyl Koiaplex has formed,

the heating mixture is cooled below about 25 ° C and the insoluble one Complex is separated from the purified oxime.

In the method according to the invention, the roheri Oximes treated with urea or thiourea in the presence of a mixture of water and an inert solvent, to form a carbonyl-urea complex that is present in the reaction medium is relatively insoluble. The insolubility of the complex is exploited to separate the carbonyl complex from the soluble Separate Oxira and the oxime in a purified and / or concentrated form by extraction with a suitable Solvent system or any other common one Cleaning method. More specifically, the mixture of crude oxime, ketone and organic chlorides is made with Urea or thiourea, water and / or lower alkanol treated at elevated temperature until the chlorides are converted into ketones and urea or thiourea-ketone complexes have formed; then it is cooled down, the insoluble urea or thiourea-ketone complexes separated from the oxime-rich piltrate by filtration, the purified oxime is concentrated by solvent extraction or an equivalent method and, if desired, further purified by extraction and / or distillation under reduced pressure.

In the practical implementation of the method according to the invention, an oxime product which is produced with considerable! -! Narrow of Carbonyl compounds and / or organic chlorine compounds is contaminated, at elevated temperatures in an Iiedium

6 0 S H? 1 / Π 9 ^ ^

- * - ■? 5 4 7 A 6

from water and inert solvents with urea or thiourea treated. (If in the following, with the exception of the examples, "urea" is used, this designation closes "Thiourea"). A sufficient amount of urea must be used to remove all carbonyl impurities be converted into a urea complex which is insoluble in the reaction medium. The heating is continued while stirring continued until the organic chlorides are decomposed. Then the reaction medium is cooled and the urea complex was cancelled. At this point the insoluble urea carbonyl complex is usually separated from the oxime and continued to be used.

In a preferred embodiment of the invention, a paraffin-on-oxime product with 5-30 carbon atoms or more, an oxime content of at most 95% by weight and considerable amounts of impurities in the form of carbonyl and. Chlorine compounds at about 25 - 100 wt .-% of urea treated (based on the amount to be cleaned raw oxime), to form a reaction mixture - 200 ⁰ C in the presence of a mixture of water and lower alkanol by 10. Heating of this mixture is continued until the organic chlorides are decomposed; then the mixture is cooled to facilitate the precipitation of the urea-carbonyl complex, which is separated from the purified oxime for further use and / or purification.

In a particularly preferred embodiment of the invention, the starting point is a crude oxime which is photolytic Nitrosation of · C ^ q-C. , - η-Para ff inen with nitrosyl chloride and hydrogen chloride has been obtained and an oxime content of max. 95 wt .-% and up to 10 wt .-% or above it contains ketones and organic chlorides as impurities. This crude oxime will

a) about 10 - 100 wt .-% of urea is mixed in the presence of 1-20 wt .-% of water and 2-50 wt .-% of methanol, then heated to about 25-125 ⁰ C, until the

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thermally unstable chlorides decompose xmd into ketones over leads s ind,

b) cooled to below 25 C to prevent the precipitation of all ketones as an insoluble urea-ketone complex to facilitate; the work-up is carried out by

c) Filtration to remove the urea-ketone complex of the purified oxime dissolved in the filtrate, and

d) Extracting or distilling the filtrate to obtain the to obtain purified oxime contained therein.

Detailed description of the invention:

A. The paraffinone oximes suitable for carrying out the invention:

Every oxime, especially paraffin oxime, at least Containing 5-30 or more carbon atoms can be used as feed as long as they are in substantial amounts contain carbonyl and / or organic chlorine compounds as impurities. Cheap oximes are the linear ones and cyclic raw oximes, such as: hexanone oxime, cyclohexanone oxime, heptanone oxime, octanone oxime, uronanone oxime, Dekanonoxime, Undekanonoxime, Dodecanonoxime and their higher homologues and / or mixtures thereof. The preferred oximes are crude cyclohexanone oximes and the paraffinono xime with 10-15 carbon atoms and an oxime content of 95% or below. They can be in the form of the relatively dry raw individual oximes, free of inert solvents, or as a mixture of oximes with 10-15 C atoms, either largely free of solvents or containing up to 25% by weight of inert solvent. The group of oximes with 10-15 carbon atoms, whether solvent-free or not, is preferred because they are in large Amounts from the nitrosation of the corresponding paraffins according to the German patent application mentioned at the beginning P 21 15 049 are available.

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B. The complexing agent urea "or thiourea:

The complexing agent is selected from the group consisting of urea, thiourea, and mixtures thereof. These reagents are used in sufficient quantities so that at least all of the ketones contained in the crude oxime, including the ketones that arose from the decomposition of the chlorides that were originally present in the oxime. which are complex-bound can be grounded. The complexing agents are usually used in excess (based on the ketones and the ketones formed from the chlorides). Thus, if 5 - 10 ° / ° ketones oxime present, are from 10 to 100 wt .- / ο urea, based on the Ausgangsoxim used. If thiourea is used, an amount commensurate with the higher molecular weight of this compound is required.

C. Water:

Pure sufficient removal of the ketones (or aldehydes) of the crude oximes, the presence of water during the formation of the urea carbonyl complex is essential. Satisfactory results are obtained when about 1-20% by weight of water, based on the amount of oximes, preferably 4-15% by weight of water is present during complex formation. The presence of VJasser also leads for the conversion (during the heating ^) of the nitrosochlorides and similar compounds present in ketones which then form a complex with the urea. As from the Examples 6-12 which follow later can be seen, however, a satisfactory removal of the ketones or aldehydes can only be achieved from the crude oxime in the presence of a water-alkanol system, especially when in 0.1-2 moles of water are present in this system per mole of alkanol.

D.Cosolvent:

As stated above, water and at least one inert, water-miscible solvent must be used be to the. Carbony! Impurities from the crude oxime

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by separating the urea complex, which is in your Reaction medium -insoluble, can be removed. Even though all alkenols with 1-5 carbon atoms are suitable and methanol is preferred, other inert solvents can also be used be used. Such solvents are, for example, acetone, ethyl ethyl ketone and methyl acetate.

Ε «, solvent for washing the urea-carbonyl complex:

To avoid oxime losses by including oximes in the insoluble ones To bring urea complexes to a minimum, can with solvents in which urea or thiourea has limited solubility, i.e. in which less than 0.1 wt * ~% urea are soluble, are washed.

C. Reaction conditions:

(1) Temperature - The necessary for the inventive process, reaction temperatures are relatively flexible and are in the range of about 25-200 ⁰ C. Since the best results are obtained in the temperature range of about 25 to 125 ° C, this is the preferred temperature range.

(2) Pressure - Atmospheric or near atmospheric pressure is commonly used. There are no visible advantages result from the application of positive or negative pressure and costly to maintain such prints atmospheric pressure is preferred.

(3) Reaction Time - The reaction time varies with the reaction temperature and the concentration of the starting material, as well as with the size of the approach that is being treated. For these reasons, the response time may not be accurate can be specified. However, under most conditions, the reaction is within 0.1-12 hours Treatment terminated, long periods not being harmful.

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Among the most common reaction conditions is the reaction completed within about 1-2 stages.

(4) Separation of the pesticides - The separation of the precipitated Carbonyl urea complex and the exclusion included Oxime is obtained by viewing the complex with solvents, in which the urea has limited solubility. Such solvents are, for example, alkanes from pentane to decane and mixtures thereof, cycloalkanes, cyclohexenes, cold alkanols with 1-5 carbon atoms and mixtures thereof as well Ketones with 3-10 C atoms and mixtures thereof.

(5) Mo! Ratio of urea or thiourea to crude Oxime - Good results are obtained if 0.3-3.0 moles of urea are used per mole of oxime to be purified. Particularly However, good results are obtained with a urea to oxime molar ratio in the range of 0.5-2.0.

(6) Molar ratio of urea zxx ketone in the oxime -

A molar ratio of 5-50 moles of urea or thiourea per mole of ketone in the crude oxime ensures good cleaning. A ratio of about 10-25 moles of urea per gram of ketone present in the oxine is preferred. The narrower mole range is preferred because it gives consistently good yields on purified oxime, which is practically free from carbonyl compounds, in particular ketones, can be obtained.

G. Procedure conditions:

As described above, this invention is based on the discovery that the oxime content of the crude oximes is reduced by a corresponding reduction in carbonyl compounds (essentially Ketones) and the organic chlorine compounds by treating the crude oxime with urea or thiourea can be increased significantly in a water-solvent system. Obviously, oximes do not form urea coders in these systems Thiourea) complexes (the closest prior art is Ind. Eng. Chem. Vol.47, pages 216-222),

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rather, insoluble urea carbonyl complexes are formed very easily. This is especially beneficial when raw Oximes are present that contain 90-95% by weight of oximes and 5-10% by weight Carbonyl compounds, predominantly ketones, and chlorine compounds contained as impurities. Crude oximes of this kind fall during photographic ITitrosation on, especially in the photolytic ITitrosation of η-paraffins. Strangely, carbonyl compounds can be and chlorine compounds obtained from photolytically catalyzed ITitrosation of η-paraffins Do not remove oximes by distillation, even molecular distillation, unless treatment with one strong base preceded. To do this, refer to the UH- *. PS 3 7 ° 4 622 pointed out. This known method has the disadvantage that the ketones are obtained as a heavy residue condensate that can only be discarded during the method according to the invention easily recovered the ketones and can be sold as chemical products. In addition, the urea-ketone complexes are formed selectively, even in the presence of a large excess of C ^ q-C ^, c-Paraf f inoximen.

In a particularly preferred embodiment of the invention Procedure runs the purification of the crude

Oxiias in the following stages:

,. on

Cu mixing a raw nC. ₍ - ₎ _. _I --Paraffnjr / _i oxime consisting of 90-95% oxime, 5-10 wt .-% ketone and about 0-5 ° / o chlorine compounds (based on initial Oximgehalt asu), having about 15-70 wt? " Urea in the presence of 4-15% and 5-30 wt _# -% of a lower alkanol, 0.5 - 5 hours at about 85-125 C, the organic chlorine compounds to be converted into ketones, and a mixture of soluble and insoluble urea oxine To form ketone complex;

(2) cooling the mixture of soluble oxime and insoluble urea-ketone complex to about -10 to +10 ⁰ C, separating the insoluble complex from the soluble oxime by filtration, centrifugation or the like;

609821/0973

(3) washing the insoluble urea-ketone complex with a solvent in which urea has only limited solubility, and combining the washing liquid with the oxime-rich piltrate; and

(4) recovering the oxime from the liquid consisting of Filtrate and wash water.

H. Distilling in a high vacuum:

The purified oxime obtained by distilling off the solvent can be further purified by high vacuum distillation, in particular in order to remove discoloration. High vacuum distillation is understood here to mean a distillation which is carried out at a pressure below 10 mm Hg, preferably below 1 mm Hg. Although no particular vacuum distillation method is required, it should be noted that particular results are obtained when using methods of molecular distillation, which are therefore particularly preferred. Molecular distillations are understood here to mean those distillations in which the vapor path of the molecules that distill is not obstructed and the condenser in the distillation device from the evaporator by a distance which is smaller than the mean free path of the evaporating emerging molecules. Molecular distillation is preferred in the present Pail because the strong reduction in the degree of contamination of the oxirase achieved by the treatment is largely retained. Molecular distillations can be performed in a variety of vacuum equipment in the range of 0.001 to 0.0001 mm Hg. Two types of commercially available devices that are widely used operate with either centrifugal or continuous, (or falling) PiIm. Such devices are described, for example, in Chemical Engineering Handbook by Perry, Chilton and Kirkpatrick, 4th Edition, McGraw Hill Inc., New York, NX Chapter 17, pp. 29-32.

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The invention will now be described in more detail by means of examples.

Execution A - production of a crude C.Q-C ^ paraffinone oxime mixture, d.as through considerable amounts of carbonyl compounds is contaminated:

22.981 kg of a CQ-C ^ -n-paraffin mixture is placed in a photoreactor which is provided with heating and cooling devices and in which light of a wavelength below 200 millimicrons can get from a light source. The paraffin mixture is reacted with an excess of gaseous nitrosyl chloride at 15.6 ⁰ C in the presence of gaseous hydrogen chloride, wherein the flow velocities g / be 1,64- and 0.95 min. After the crude oxime-acid salt has been separated off, the acid is neutralized with aqueous ammonia and the crude oxime mixture is isolated. The molar selectivity to crude oximes is 87.4 % with a total yield of 90.7% by weight oxime. The crude oxime contains about 4 wt% ^ io ~ ^ 1 ^ ketones.

example 1

Attempt to purify neutralized crude C ^ qC _x , -, - n-paraffinone oxime using the usual vacuum distillation -

800 g of the C.Q-C ^ -n- Paraffinonoxiragemisch.es obtained according to execution A, the 4.3 wt% ketones and 0.41 wt% chlorine contains, in a vacuum at 0.4- - 0.6 mm / over a 4-5.7 approx long Hempel column, the 6.55 am long, into the column Has protruding stainless steel obstacles in the presence of 100 g 571 ° C hydrocarbon driver (chaser) fractionated. The results are summarized below:

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Fraction-Ur. boiling point
⁰ C pressure
mm Hg Weight, G G. wt .-%
Ketones in
the Frekticr 1 100 o, 5 6.0 50 2 110 0.6 74.0 19th 3 108 0.4 164.1 13th 4th 108 0.4 204.3 9 5 112 0.4 101.2 13th 6th 120 0.5. ■ 57.0 19.5 7th 150 0.6 58.2 30th

V / ie the increase in ketones (weight gain over 175) shows, the usual vacuum stills tion worsens without prior treatment with urea to remove the ketone impurities the purity of the oxime product. The distillate looks undesirably cloudy.

Example 2

Attempt to purify crude C ^ Q-C ^ -n paraffin oxime mixture using continuous thin film distillation (Distillation under high vacuum) without prior purification with urea -

90 g of the C.Q-C ^ paraffinone oxime mixture obtained according to embodiment A, containing 3.6 wt% ketones and 1.15 wt% chlorine is placed in a 50.8 mm IHiniifilm high vacuum evaporator (Rodney Hunt Vacu-Film Processor the Firna Rodney Hunt Nachine Company) and this to 100 - 105 C. heated at 0.3 mm Hg. A light colored oxime distillate (67.0 g) containing 2.6% by weight ketones and 0.93% by weight chlorine, is received. The product looks undesirably cloudy.

This example shows that without the treatment according to the invention with urea or thiourea to remove the ketones, the continuous thin-film distillation does not Effective measure to remove carbonyl and chlorine contaminants is made from raw oxime.

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example

Failure of urea to remove impurities from crude mixtures of C ^ qC _x . ₇ -Paraffinone oximes (obtained by photolytic nitrosation of η-paraffins), if water is not aggressive during complex formation -

50 g of the C ^ ₀ -C, .-, - n-Paraffinonoximgemis.ches obtained according to embodiment A, which contains about 5% by weight of ketones and 1.5% by weight of chlorine, is mixed with 500 ml of mixed heptanes, 20 ml of methanol and 50 g of urea are mixed in a reaction vessel and heated to 22 ° C. for 1 hour. After filtering off the precipitated crystal complexes in vacuo, the crystals are washed with 50 ml of mixed Eeptsnen and deionized in 200 ml. Dissolved in water. The aqueous solution contains only a trace of ketone impurities after extracting twice with 100 ml of diethyl ether, combining the ether extracts and evaporating the ether. The filtrate and wash solutions, presumably oxime free of ketones, are collected and washed with 200 ml of deionized water, dried and vacuum stripped to recover 41 g of oxime. The analysis shows, however, that the ketone content is not significantly below the initial concentration, that is to say not particularly below 5% by weight. This, along with the following examples, shows that water must be acidic for effective urea-ketone complex formation, by which the ketones are removed from the crude oxime. Replacing the urea with an equal molar amount of thiourea is also ineffective in removing the ketones from the crude oxime in the absence of water.

Example 4

Urea failure to remove ketone impurities - from crude oximes in the presence of lower alkanols, but absence of water during complex formation -

120 g of urea and 500 ml of absolute methanol are heated, until reflux begins, then 20 g of crude n-C.Q-C ^ .-, - oxime mixture (which contains 5% by weight of ketone and 1.5% by weight of chlorine

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contains) and 100 ml of mixed heptanes are added to the stirred refluxing urea solution. The reaction is stopped every 2 hours and the reaction mixture is cooled ^{to about 5 ° G.} The crystalline complex that has formed is isolated by vacuum filtration. The crystals are washed twice with 50 ml of mixed Hep thaw and then dissolved in 200 ml of deionized water. The resulting solution is extracted twice with 100 ml of diethyl ether each time. The iither is evaporated under vacuum, after which only 0.02 g of ketone is obtained. The filtrate and the washing solutions are washed with 200 ml of deionized water, dried and the solvent is stripped off, with. 16 g of Oxira can be recovered. Analysis of the oxime product shows that virtually no ketones have been removed. If the same molar amount of ethanol is used instead of methanol, the same poor results are obtained.

Example 5

Failure of urea to remove ketone impurities from crude oxime when complex formation is carried out in the presence of water but in the absence of a lower alkanol.

50 g of a crude nC ^ Q-CL ₇ oxime mixture (containing 4.3 % by weight of ketones and 1.12% by weight of chlorine) and 100 g of distilled water are refluxed for three hours. After cooling, the mixture is extracted twice with 100 ml of cyclohexane, the collected cyclohexane extracts are stripped in vacuo in order to remove the cyclohexane. Sine 3Ί ~ g portion of the oxime which was retained in the Cyclohexanextraktion (which 7? 2 wt .-% ketone contains), is mixed with 25 g of urea and 25 ml of absolute methanol and the mixture kept pO minutes at 22 ⁰ C. After cooling to about 5 ° C. in an ice bath, the urea complex crystals which have precipitated out are isolated by vacuum filtration. The crystals are then dissolved in 30 ml v / water and the aqueous solution is extracted twice with 20 ml diethyl ether each time.

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From the combined ether extracts 1 g of liquid containing polygamy 4-0% by weight of ketones is recovered by evaporation of the ether. The oxime-rich filtrate from the Eristoll filtration is diluted with ^ O ml of water and extracted twice with 100 ml of diethyl ether each time. The collected ether extracts are stripped, 28 g of oxime containing 4.9 % by weight of ketone being obtained. Not only are poor oxime yields obtained, but the decrease in oxime causes the ketone content to rise (from 4.3% by weight to 4.9% by weight) above the ketone content that the Oxira had before treatment exhibited.

Example 6-12

In each of the following examples, 187 g of crude oximes prepared according to Execution A, which contain 4.3 g% by weight Contained ketone, with urea in amounts ranging from 30-120 g in the presence of methanol, in amounts ranging from 0 (Example 11) to 50 g "^ d water in amounts in the range of 9-20 g brought into contact. The procedure consisted of the general off the steps

(a) heating the reaction mixture of crude oxime or

Oximes, methanol (excluding Example 11) and water

under reflux to reflux and 1 hour long Ruhrerv to the decompose organic chlorine compounds and urea To form ketone complexes;

(b) cooling the reaction mixture to a temperature in the range of -10 to +10 ⁰ C, until the TJnlöslichkeit

'the urea complex is optimal;

(c) filtering off the crystals and. Wash with 10-50 parts of methanol from about -10 to + 10 ⁰ Cj

(d) diluting the oxime-rich filtrate to which the methanol wash liquid is added, with 100 ml v / ater and twice extracting with 50-100 ml ether to get the To remove oximes from the filtrate and wash solution ·;

(e) Remove the ether by stripping to the purified Obtain oxime.

The examples are compiled in the following table:

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TABEL

Composite of the
Input material 6th 7th B. e i s ρ i 187
4.3 e 1 e 11 187
4.3 12th 8th · 9 120
32
2, 'o
42.5
4.0 10 according to example 1 30th
9
0.5
10.6
2.0 C _{1 n} -Cp, OXIME ^ ^a ^ 187
4.3 187
4.3 manufactured 190
1.0 187
4.3 190
1.0 187
4.3 Weight, g
% By weight of ketones 120
50
20th
2.0
42.5
. 1.8 60
32
18th
1.0
21.25
1.0 18?
4.3 161.2
1.6 30th
16
9
0.5
10.6
2.0 174.8 ^(b)
4.8 60
16
18th
1.0
21.25
1.0 I. Urea, g
Methanol, g
Water, g
Urea / oxime, molar ratio
Harn stο ff / ketone, Mo1 ratio.
Urea / Oxime / Water, Mol-Ver 190
1.0 190
1.0 60
32
9
1.0
21.25
2.0 19.3
40 190
1.0 3.2
9.3 190
2.0 i Treatment temperature
Duration of the temperature treatment,
hours 132.4
0.75 133.6
1.8 190
1.0 161.4
3.1 162.7 ^Cb)
2.0 K) Recovery
Stripped filtrate
Weight, g
Wt% ketones 16.5
40 38.8
10.8 1 ^) 8.9
1.4 15.0
40 14.3
40 Product made from urea
crystals
Weight, g
Wt% ketones 44.6
10.5

(a) Oxime, which contains 1.12% by weight of chlorine

■ ■

(Id) The urea crystals were washed with gasoline before decomposition

Form B - preparation of a specific oxime, the significant amounts of carbonyl compounds as impurities contains:

Using the procedure described in Sedgwick, "Organic Chemistry of Nitrogen", pp. 169-175 (1937), 1.2 mol of 6-undecanone are reacted with an alcoholic solution of 1 mol of hydroxylamine at room temperature, where 0 , 8 Hole 6-undecanonoxim., CH ₇ . (CH ₂ ) ₄ <f (CH ₂ ^ GH ₅ , vras is contaminated with 5.5% 6-undecanone, can be obtained.

Example 13

Purification of a specific paraffin oxime that is produced by considerable Plengen carbonyl compounds is contaminated.

The 0.8 hol o-undecanonoxira obtained in embodiment 3 are carefully mixed with 50 g of absolute alcohol, 20 ml of water and 120 g of urea. This reaction mixture is heated under reflux for 2 hours, then ^{cooled to about 0} ° C., the urea-ketone complex which has precipitated at this temperature is filtered off and washed with 20 ml of cooled methanol in order to remove entrapped oxime. The piltrate is then diluted with 100 ml of water under methanol, extracted twice with diethyl ether and then the solvent is stripped off in vacuo, after which purified 6-undekanono3cLiii is obtained which contains about 0.7% by weight of ketones.

This example shows:

(1) that the inventive method for cleaning specific oxime is just as suitable as for the purification of oxime mixtures, and

(2) that the method according to the invention can also be used on crude oximes that are not photolytic nitrosated have been received.

As the various examples have shown, this is according to the invention Process for purifying oxiaen over the prior art both surprising and advantageous.

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Although a large group of compounds, including ketones, are known to interact with urea as well as thiourea Form complexes, it was not known that crude oximes, which contain ketones and organic chlorine compounds, can be freed from these compounds by adding the urea or thiourea complexes of the ketones to the raw oxines are produced »It was also completely surprising to find that the oxime purification process not only requires the formation of the urea-ketone complexes is, but that little or no ketones are removed from crude oils. Oximes as urea-ketone complex can, if not about 4-15% by weight of water along with lower alkanol during the formation of the urea complex are present. This is shown by Examples 1-5 given above. In addition, the process according to the invention offers the advantage that the organic chlorine compounds during heating (usually under reflux.) To form the Urea-ketoii complex are decomposed. Since the chlorine-containing Compounds are converted into ketones

the

by adding urea these ketones as well as the /; originally in which raw Oxirn were present, complex-bound. In contrast to the usual oxime purification, the invention

d'i β method according to the advantage that with him / removed ketones incurred in a salable form. Other advantages are to see that in the method according to the invention the Usual methods can be used, higher Eeaktion temperatures and pressures are not required and the Urea or thiourea costs are low, with the compounds easily cleaned and reused can be. While water is essential in complex formation, the lower alkanes, especially methanol or ethanol can be used as a cosolvent, and the purified oxime can by any of the known methods, such as molecular distillation and / or chromatographic separation can be further purified.

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Claims (3)

Claims 1) Process for the purification of a crude Cc-C- _n -Psr äff iii ~ onoxime or oxime mixture with an oxime content of max. 95% by weight, which is contaminated with carbonyl and chlorine compounds, is characterized by the fact that a mixture of the paraffin-on oxime to be purified and, based on 1 part by weight of this paraffin-on oxime, is about 0 .01 "to 0.2 parts by weight of water and about 0.02-0.5 parts by weight of an alkanol with 1-5 carbon atoms, 0.1-1 part by weight of urea" or thiourea are added, this reaction mixture to 25-200 ⁰ C is heated until the oceanic chlorine compounds are decomposed and an insoluble urea or thiourea carbonyl complex has formed, the reaction mixture cooled below about 25 ° C and the insoluble complex separated from the purified oxime will. 2) Method according to claim 1 for cleaning raw ^^ o ~ ^ 15 ~ Paraffin-on-oxime produced by photocatalytic ITitrosie tion of η-paraffins have been obtained and by. ° more up to and / 10% by weight of ketones and organic chlorine compounds are contaminated, characterized in that 0.1-1 part by weight of urea or thiourea are added to the mixture in the presence of the water-alkanol mixture, this reaction mixture being 0, 5-5 hours is heated to 25-125 ° C until the chlorine compounds are decomposed and the insoluble complex has formed, the reaction mixture is ^{cooled to -10 to +10 0} C within at least 0.2 hours, the insoluble complex is separated and the purified oxime is isolated. 6 0 9 8 21/0973 ■ - 20 - 3) Method according to claim 1 or 2,. through this characterized in that the alkanol is methanol used and the complex is formed with urea. 4-) Method according to claim 3j, characterized in that the insoluble complex • is ^{washed with methanol cooled down to at least +10 0} C, the washing solutions are added to the reaction mixture, the mixture is extracted at least twice with dialkyl ether and the purified oxime is removed by distilling off the solvent is isolated in a vacuum. 609821/0973